Esshete 1250

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Sandvik materials.

Esshete 1250 is a fully austenitic chromium-nickel steel with excellent high- temperature strength and good resistance to corrosion in boiler applications. The grade can be used at temperatures up to about 650°C (1200°F), it is easily fabricated and also characterized by:

High strength in relation to other typical candidate austenitic alloys

Very good resistance to steam and flue gas atmospheres

Good structural stability at high temperatures

Good weldability

Standards

UNS: S21500

EN Number: 1.4982

EN Name: X10CrNiMoMnNbVB15-10-1

Product standards

ASTM A213

EN 10216-5

Approvals

VdTÜV-Werkstoffblatt 520

PED (Pressure Equipment Directive) 2014/68/EU

Chemical composition (nominal)

Chemical composition (nominal) %

C

Si

Mn

P

S

Cr

Ni

Mo

V

Nb

B

0.1

0.5

6.3

≤0.035

≤0.015

15

9.5

1.0

0.3

1.0

0.005

Applications

The high creep strength of Esshete 1250, combined with its good resistance to steam and flue gas atmospheres, makes it a very suitable material for use in coal-fired boilers. The grade was developed in the United Kingdom in the 1960's, and the bulk of the material has been used in the UK power industry in 500 and 660 MW boilers.

The main application has been superheaters and reheaters operating at 570oC (1058oF), steam pressure 170 bar (superheaters) and 40 bar (reheaters). Typical metal temperature 600–700oC (1112–1292oF), in flue gas temperature 900–1200oC (1652–2192oF). The corrosion environment on the fireside in the UK boilers was historically very aggressive as the British coal has, typically a high chlorine content of up to 0.6%, sulphur at 1–2% and a high ash content of 20%.

Esshete 1250 has also been used successfully in superheaters in biomass boilers, burning various biofuels and producing steam at 580–540oC (1076–1004oF) at 60–200 bars pressure.

Trademark information: Esshete 1250 is a trademark owned by Corus

Corrosion resistance

Air

Good resistance to scaling up to 800°C (1472oF).

Gaseous corrosion

Good resistance to steam and flue gas atmospheres. In service conditions typical of coal-fired boilers, the alloy has a very similar fireside corrosion to alloys of the ASTM 316H type. However, the much increased high-temperature strength gives significantly improved service performance. Fireside corrosion resistance in coal-fired, biomass-fired or coal/biomass co-fired boilers is similar to that of type ASTM 347H. Steam-side corrosion is similar to that of type ASTM 347H.

Bending

Esshete 1250 can be cold bent to narrow bending radii. Heat treatment after cold bending is not normally necessary, but this must be decided after considering the degree of bending and the operating conditions.

If post bending heat treatment is carried out, it should be in the form of solution annealing.

Hot bending is carried out at 1100–850°C (1832–1652°F) and should be followed by solution annealing.

Forms of supply

Seamless tube and pipe in Esshete 1250 is supplied in dimensions up to 260 mm (10.24 in.) outside diameter, in the solution annealed and white-pickled condition or in the bright annealed condition.

Heat treatment

Tubes are delivered in the heat treated condition. If another heat treatment is needed after further processing the following is recommended:

a) Rp0.2 and Rp1.0 correspond to 0.2% offset and 1.0% offset yield strengths, respectively.
b) Based on L0 = 5.65 √S0 where L0 is the original gauge length and S0 the original cross-sectional area.

At high temperatures

Metric units

Temperature

Proof strength

Rp.02

Rp1.0

°C

MPa

MPa

min.

min.

50

213

254

100

188

232

150

171

210

200

161

195

250

153

190

300

148

187

350

145

184

400

144

182

450

141

179

500

139

178

550

136

175

600

133

170

650

130

165

700

125

159

Imperial units

Temperature

Proof strength

Rp.02

Rp1.0

°F

ksi

ksi

min.

min.

100

31.2

37.4

200

27.9

33.7

300

25.1

30.8

400

23.1

28.6

500

21.7

27.1

600

21.0

26.4

700

20.8

26.2

800

20.6

26.1

900

20.3

25.8

1000

19.8

25.4

1100

19.3

24.7

1200

18.7

23.9

1300

18.1

22.9

Creep strength

The creep rupture strength values correspond to values evaluated by Sterling tubes Ltd. The data from creep tests made by Sandvik correspond well to the given data.

Metric units

Temperature

Creep rupture strength, MPa

°C

10 000 h

100 000 h

250 000h

600

241

199

177

610

231

185

158

620

221

167

134

630

210

147

109*

640

198

122

90*

650

184

100

78*

660

167

84

69*

670

147

74

52*

680

124

66

56*

690

102

59

51*

700

86

54

46*

710

75

49

42*

720

67

45

37*

730

61

40*

32*

740

55

36*

-

750

51

30*

-

760

46

-

-

770

42

-

-

780

38

-

-

790

34

-

-

* Values, which have involved extended stress/time extrapolation

Imperial units

Temperature

Creep rupture strength, ksi

°F

10 000 h

100 000 h

250 000 h

1100

35.2

30.7

28.8

1125

33.9

27.2

23.3

1150

32.0

23.5

18.5

1175

29.6

19.5

14.6*

1200

26.7

15.3

11.5*

1225

23.2

10.7

9.2*

1250

19.1

9.8

8.3*

1275

14.5

8.6

7.3*

1300

11.6

7.5

6.3*

1325

10.0

6.4

5.3*

1350

8.6

5.5

4.4*

1375

7.4

4.6

-

1400

6.5

3.9

-

1425

5.7

-

-

1450

5.1

-

-

* Values, which have involved extended stress/time extrapolation

Physical properties

Density: 7.9 g/cm3, 0.29 lb/in3

Thermal conductivity

Temperature, °C

W/m °C

Temperature, °F

Btu/ft h°F

20

13

68

7

100

14

200

8

200

15

400

9

300

17

600

10

400

19

800

11

500

20

1000

12

600

22

1200

13

700

23

1400

13.5

800

24

1500

14

Specific heat capacity1)

Temperature, °C

J/kg °C

Temperature, °F

Btu/lb °F

20-100

505

68-200

0.12

20-200

530

68-400

0.13

20-300

540

68-600

0.13

20-400

545

68-800

0.13

20-500

555

68-1000

0.13

20-600

560

68-1200

0.13

20-700

565

68-1400

0.14

20-800

575

68-1600

0.14

20-900

580

68-1800

0.14

20-1000

585

-

-

1) Mean values in temperature ranges

Thermal expansion1)

Temperature, °C

Per °C

Temperature, °F

Per °F

20-100

15

68-200

8.5

20-200

16

68-400

9

20-300

17

68-600

9.5

20-400

18

68-800

10

20-500

18.5

68-1000

10.5

20-600

19

68-1200

10.5

20-700

19

68-1400

11

20-800

19.5

68-1600

11

20-900

20

68-1800

11

20-1000

20

-

-

1) Mean values in temperature ranges (x10-6)

Resistivity

Temperature, °C

μΩm

Temperature, °F

μΩin.

20

0.74

68

29.1

100

0.80

200

31.3

200

0.88

400

34.6

300

0.94

600

37.5

400

1.00

800

39.9

500

1.05

1000

41.8

600

1.09

1200

43.6

700

1.13

1400

45.1

800

1.16

1600

46.3

900

1.18

1800

47.2

1000

1.20

-

-

Modulus of elasticity1)

Temperature, °C

MPa

Temperature, °F

ksi

20

192

68

27.8

100

184

200

26.6

200

176

400

25.5

300

168

600

24.2

400

160

800

22.9

500

151

1000

21.5

600

143

1200

20.2

700

135

1400

18.9

800

127

1600

17.7

900

120

-

-

1) (x103)

Structural stability

As in other austenitic stainless steels, sigma phase can be formed after long heat treatment in the range 550–950°C (1022–1742oF). Due to the low chromium content, Esshete 1250 is significantly less sensitive to sigma phase formation than steels of e.g. the ASTM 316 type, according to tests involving ageing for 100000 h.

Welding

The weldability of Esshete 1250 is good. Welding must be carried out without preheating and subsequent heat treatment is normally not required. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

For Esshete 1250, heat input of <1.5 kJ/mm and interpass temperature of <150°C (300°F) are recommended.

Recommended filler metals

TIG/GTAW or MIG/GMAW welding

ISO 18274 S Ni 6082 / AWS A5.14 ERNiCr-3 (e.g. Exaton Ni72HP)

MMA/SMAW welding

ISO 14172 E Ni 6182/ AWS A5.11 ENiCrFe-3 (e.g. Exaton Ni71)

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Sandvik materials.